This invention relates to a method for regenerating a moist adsorption medium, particularly an adsorption medium in a multiple bed drying system. The invention further relates to an apparatus for carrying out the method of the invention.
A multiple desiccant bed system used for drying a synthetic plastic material is known, for example, from Noguchi, U.S. Pat. No. 4,601,114, the entire disclosure of which is expressly incorporated by reference herein.
A moisture-laden gas stream is formed as the exit gas from a hopper in which plastic granules are dried by a stream of drying air. The exit gas is conducted through one or more drying vessels filled with an adsorption medium, whereby the adsorption medium extracts the moisture from the gas so that the resulting dry gas can be used again as a drying gas for drying plastic granules.
When the adsorption medium in a drying vessel is saturated with moisture, the drying vessel is transferred to a regeneration phase in which heated outside air is conducted through the adsorption medium which takes up and carries away the moisture which was adsorbed therein. The outside air used to dry the adsorption medium typically contains moisture, which increases the drying time required to regenerate the adsorption medium.